<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>从小到大判断成绩</title>
</head>

<body>
    <script>
        let num = prompt('请输入你的成绩')
        if (num < 60) {
            alert('挨揍')
        } else if (num >= 60) {
            alert('努力，差一点就挨揍')
        } else if (num >= 70) {
            alert('努力，争取更好')
        } else if (num >= 80) {
            alert('加油，不错')
        } else if (num >= 90) {
            alert('厉害不错')
        } else {
            alert('输入正确的成绩')
        }
    </script>
</body>

</html>